1 Kinetic Particle Theory

Kinetic particle theory states that:

1. Particles too small to be seen directly2. Spaces exist between particles of matter; and the amt of space between particles differ

in S,L,G states.3. Particles of matter are in constant random motion, and move at different speeds

Solid Liquid GasShape Fixed shape

(Particles of solid held together by very strong forces of attraction. They cannot move about freely, and only have enough energy to vibrate about their fixed positions)

No fixed shape

(Forces of attraction between particles of liquid < in solid. Particles of liquid not held in fixed positions, they are arranged in a disorderly manner and can move freely by sliding over one another)

No fixed shape

(Particles of gas have a lot of energy and are not held in fixed positions. They can move rapidly in any direction)

Compression Not compressible

(particles are already v close)

Not compressible

(particles are still quite close to one another)

Compressible

(particles are v far apart)

Volume Fixed volume

Non compressible since particles v close, thus fixed volume

Fixed volume

Particles of liquid still quite close, thus non compressible and fixed volume

No fixed volume

Particles of gas v far apart can be forced to move closer no fixed volume

Changes of State

Take in Heat

(Melting , Boiling)

Give out Heat

(Freezing)Straight line portion of the graph (be it upward sloping/ downward sloping)

Heat energy taken in/ given out but NO TEMPERATURE CHANGE

Why?o Melting

Temp remains constant as heat energy taken in to overcome forces of attraction between solid particles to become liquid state

o Boiling Temp remains constant during boiling as heat energy is absorbed to break all

the forces holding particles of liquid together (to get into gaseous state)o Freezing

Temp remains constant during freezing as heat energy released as particles slow down to take up fixed & orderly positions in solid (Kinetic energy proportional to temperature)

*Pure substance:o Melting point = freezing pointo Boiling point = condensation point

Answering qns on behavior of particles at _1__ temp to _2___ temp:- State the state of particles at (initial) temp- Describe motion + arrangement of particles at (initial) temp- Describe new state- Describe motion + arrangement at (final) temp- Describe motion and arrangement of new state

Evaporation VS Boiling

Evaporation BoilingProcess by which liquid changes to a gas at temperature < boiling point

Process by which liquid changes to gas at BOILING POINT

Occurs only at surface of liquid Occurs throughout the liquidOccurs slowly Occurs rapidly

Condensation/ Sublimation

Condensation:

- Gas to liquid- Useful process to condense gas to liquid for easy storage and transport since liquid

smaller volume

Sublimation:

- Solid to gas DIRECTLY without passing through liquid state (melting)- Eg: carbon dioxide (dry ice) , iodine- Reverse of sublimation = condensation

Boiling/Evaporation

3 Separation and Purification

Pure substance:

- a single substance not mixed with anything else- FIXED melting & boiling points- Shows only 1 spot on chromatogram

Impure Substance:

- Substance mixed w impurities - Melt and boil OVER A RANGE OF TEMPERATURES

Purity Test

Melting point determination (for solids) - Impurities ↓ melting point

Boiling Point determination (for liquids) - Impurities ↑ boiling pointChromatography - Impurities results in > 1 spot on

chromatogram (1 intense spot + several faint spots)

Separation methods

Definition What is it used for? When is it used?

Filtration Filtration is used to separate insoluble solid particles from a liquid

a. Separate insoluble solid from liquid

b. Mixture of 2 solids after adding a suitable type of solvent to dissolve one of the soluble solid, and the other one remains insoluble.

*To see which solvent suitable either add solutions to react away one of them/can act as solvent to dissolve

Crystallization Crystallization is used for obtaining pure solid sample from its solution.

a. Mainly used for substances that have water of crystallization and those that decompose easily when heated strongly

*Crystallization occurs because

Melting point Boiling Point

solubility decrease as temperature decreases, thus need to let it cool down to allow crystals to form

Simple Distillation

Separate pure solvent (liquid) from solution

a. When you only want 1 particular liquid from a mixture of solution

Fractional distillation

Separate mixture of miscible liquids with WIDELY differing boiling points

a. When want > 1 liquid from mixture of liquids

Sublimation Solid to vapour DIRECTLY(Never undergo liquid state)

Eg. Iodine, dry ice, anhydrous iron (III) chloride, anhydrous aluminum chloride, ammonium chloride

Separating Funnel

Used to separate two immiscible liquids

a. Used when the two liquids put together form 2 distinct layers due to density difference

Boiling stones for smooth boilingBulb of thermometer near side arm so that can accurately measure the boiling point of substance that is being distilled. ( While pure substance distilling over, thermometer shows constant temperature = boiling point)Water flows against gravity so as to increase contact time between hot vapour and cold water flowing through the condenser

Glass beads in fractionating column to provide large surface area for vapour to condense onVapour of liquids with lower b.p distil over first, higher b.p vapour condense along fractionating column and re-enter round bottom flask.

ChromatographyUsed to separate & identify small amounts of substances that are dissolved in solvents

*Separation of dyes depends on differences in:

- solubilities of dyes in solvent- tendencies of dyes to stick on surface of paper (aDsorbed)

Dyes that are most soluble + least adsorbed will travel fastest

1. Why must use cover?- Prevent evaporation of solvent,

ensure that air in container is saturated with solvent vapour

2. Why must solvent front be as high up as possible?- To obtain good separation

3. Why use pencil to draw starting line?- Pen ink contain dyes, dyes will

dissolve in solvent and it will also be separated

4. Why must solvent level be below starting line?- So that dyes will travel up the

paper instead of dissolving directly into solvent

5. Why use small spots of dyes at starting line?- Prevent dyes from spreading

sideways

4 Elements, Compounds and Mixtures

Element is a PURE substance that cannot be broken down into 2 or more simpler substance by chemical processes

Fixed mp/bp Anything found at periodic table = element Anything not found at periodic table = not element

Atoms are smallest particles of an element that have the chemical properties of that element

Monoatomic elements (all noble gases) Diatomic elements (Group 7 elements eg. Oxygen, nitrogen, fluorine etc) Polyatomic elements ( 3 or more atoms)

COMPOUNDS MIXTURESCompounds pure substance containing 2 or more elements that are chemically combined in a fixed ratio

Mixtures are made up of 2 or more substance NOT chemically combined together

*** Specific differences between compounds and mixtures refer to TB page 60

5 Atomic Structure

Noble gases (Group 0 elements) inert, unreactive

Individual/monoatomic atoms Unreactive because already have stable electronic configuration

Covalent Bonding Ionic BondingElectrons SHARED Electrons TRANSFERRED Between atoms of NON-METALS Between ions of METALSResult of the attraction between nuclei of 2 atoms and pair of shared electron